Running no bms sketches me out. I keep my vesc in an open space in my garage where it could catch on fire with minimal damage if it did. I worry about overcharging a cell when charging and try to stop it around 90% to be safe. Also leaving the board on forever worries me that I could take cells too low.
I would like to gather information on the best BMS options and put something in the FAQ category about various bms options and advantages and risks of each. The few I am aware of are:
None
OWIE
Hack FM BMS
Anyone have details they would like to share on these options?
For my Pint conversion I decided to use the stock FM BMS.
Pros:
Ease of use (Recycling stock FM components)
Easy modification (Little effort involved beside bridging the connections)
Cons:
Current setup does not balance cells.
Won’t allow my charger to fully charge my 15s2p setup. (Charges pack to a max of 61v-62v)
I should note that it’s very possible my BMS is bad. Either way it charges my pack so I’m content for now. I’m planning to swap it out eventually.
Hello, Does running the stock BMS as charge only prevent the battery from being cut off when the voltage is too low? From what I understand deep discharging LiOn batts can make them unstable. I am thinking about building a custom VESC based Funwheel and am trying to figure where to get an appropriate BMS from.
I went with a 1P 21700 battery with a Daly BMS. The fit and weight is good, but range is lacking. My intentions were to use it until a proper VESC BMS was vetted, but it is taking a lot longer than expected. I personally think the stock BMS solutions like the OWIE are a waste of time.
Maybe Trammpa, but it’s not 84V and doubt it will fit?
External Balancer with a lead connector through box. I will only do this if it will work with a 20s2P 21700 pack.
Some will say the Xlite V2 works, but I’m going to wait until something is a bit more reliable and vetted… for now, I’m working on a VNR style external battery solution to hold me over
I looked at the ZBMS but it’s supposedly delayed due to a safety flaw. So as I understand it the VESC controllers themselves will cut the batteries off when the voltage sags too low correct? I read there are setting in the firmware configuration for cutoff and pushback voltage.
Most of us think a BMS’ only balances cells, but it’s real responsibility is to protect the battery. Most BMS have “Charge” and “Discharge” capabilities. The discharge side protects cell damage when discharging too low.
Yes, battery perimeters like voltage & pushback settings are adjustable in VESC, which is basically doing the job of a discharge BMS.
Most of the BMS we are looking at are “charge only”, I belive this is because of the reduced size that we need. This is fine as long as the VESC is set up correctly and respect there is no fail safe protection on the discharge side.
Some people prefer this becuse it’s not possible for the board to shut off with a low battery voltage, bit this can also cause battery damage. a properly programmed BMS and board should not shut off anyway. This was the complaint about the CBCSO, The low voltage cut off setting was set to high